Cool dusty galaxies: the impact of the Herschel and Planck missions

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Cool dusty galaxies the impact of the Herschel
and Planck missions

• Michael Rowan-Robinson
• Imperial College London

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Cool dusty galaxies the impact of the Herschel
and Planck missions

• To set the scene for the Herschel and Planck
  submillimetre missions, Im going to talk first
  about some of the key discoveries from the IRAS
  and Spitzer missions

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IRAS
1983 saw the launch of IRAS, the Infrared
Astronomical Satellite, which made the first
all-sky survey at infrared wavelengths, from
10-100 microns
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IRAS - the infrared cirrus
emission from clouds of interstellar dust in
our Galaxy, the infrared cirrus
south celestial pole
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IRAS - star forming regions
constellation Orion
LMC, the Large Magellanic Cloud
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Uultraluminous infrared galaxies
IRAS discovered ultraluminous infrared
galaxies, forming stars 100-1000 times faster
than our Galaxy, probably caused by mergers
between two galaxies this is an HST image of
Arp 220

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IRAS - dust debris disks
IRAS also discovered dust debris disks around
stars, confirmed by imaging with the Hubble
Space Telescope, evidence for planetary systems
in formation. Today over 150 exoplanets are
known.

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IRAS
the IRAS all-sky survey of infrared
point-sources white star-forming regions,
blue red giant stars, green galaxies. IRAS
detected 60,000 dusty, star-forming glaxies over
the whole sky.
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JCMT 1987
The James Clerk Maxwell Telescope is a
pioneering submillimetre telescope, on Mauna
Kea,Hawaii
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Luminous submillimetre galaxies
This was the first submillimetre survey of the
sky, using JCMT. There are several very
luminous, high- redshift, galaxies found -
galaxies in the midst of their main star and
heavy element formation.
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SPITZER, 2003
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LMC


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IC1396, the Elephants Trunk

• a dark globule inside an emission nebula
• a pair of newly formed stars have created a
  cavity
• the animation shows how the appearance changes
  from the optical, where dust absorbs light to the
  infrared where the dust radiates

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infrared emission from debris along a comet orbit


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Globular cluster, and star-forming region

M17
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SINGS - Spitzer Nearby Galaxy Survey

• 75 nearby galaxies
• detailed studies of their gas, dust, and
  star-formation rate

M81
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visible (HST) and infrared (Spitzer) images of
M51, the Whirlpool galaxy
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Sombrero galaxy
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Two interacting galaxies
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Visible and infrared images of the star-forming
galaxy Messier 82
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High-redshift galaxies with Spitzer
Spitzer is only an 85-cm telescope, but it can
detect the most distant galaxies known

• Egami et al 2005 z 6.7
• lensed galaxy with M 109 Mo,
• stellar age at least 50 Myr

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SWIRE (Spitzer Wide-Area IR Extragalactic Survey)

• Ive been mainly involved with SWIRE, a survey
  of 50 square degrees of the sky at 3.6-160
  microns.
• We found 1.5 million galaxies and have used
  their optical and near infrared colours to
  estimate their distances, and hence their
  luminosities, star-formation rates, stellar
  masses and dust masses

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optical templates for photometric redshifts
t
These are the galaxy templates we use for
estimating the redshift of the galaxies

(Rowan-Robinson et al 2008)
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Over 1 million photometric redshifts
5 optical bands, 3.6, 4.5 mm
This shows the kind of performance we achieve, a
comparison of our photometric redshifts with
spectroscopic redshifts

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SPITZER-IRS spectra of ULIRGs

• detailed infrared spectra of some ultraluminous
  infrared galaxies (ULIRGs), and our models for
  these
• (Farrah et al, 2008)

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star-formation rate v. redshift

• whole SWIREcatalogue
• strong selection effects
• consistent with strong rise to z 1.5
• (RR et al 2008)

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star formation history

• ISO showed steep rise to z1
• submm surveys and Spitzer show flat from z 1-3
• very uncertain at z gt 2-3
• Herschel surveys
• will detect thousands of high-z star-forming
  galaxies

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dust mass v. stellar mass

• for most galaxies, Mdust/M 10-6-10-2
• with expected progression through Hubble type
• highest values are galaxies with gas mass
  comparable to stellar mass, assuming usual
  gas-to-dust ratio
• dust masses are highly uncertain - need Herschel
  data

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SOURCE COUNTS AT 24 microns

• to understand the numbers of sources as a
  function of brightness, different tyes of galaxy
  need to undergo different evolutionary histories

M82
cirrus
dust tori
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COUNTS AT 8-1100 mm, ir background

• Predicted counts from 8
• 1100 microns, comparison
• with observed counts at
• 160, 850 and 1100
• microns, and with
• integrated background
• spectrum
• (Rowan-Robinson 2009)

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HERSCHEL SPACE OBSERVATORY
Herschel launch May 14th 2009, now in orbit at
L2 Science demonstration phase started two
weeks ago
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HERSCHEL SPACE OBSERVATORY
First light with PACS array
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HERSCHEL SPACE OBSERVATORY
PACS composite of M51
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HERSCHEL SPACE OBSERVATORY
SPIRE First light image
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HERSCHEL SPACE OBSERVATORY
SPIRE images of M66 and M74
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HERSCHEL SPACE OBSERVATORY
SPIRE images of M74 (and high z galaxies ?) at
250, 350, 500mm
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PLANCK Surveyor
Planck launch May 14th 2009, now in orbit at L2
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Main goal of Planck is to map microwave
background radiation
The CMB is incredibly smooth, to one part in
100,000, but the very small fluctuations, or
ripples, first mapped by the COBE mission, are
the precursors of the structure we see
today. They also tell us about the matter and
energy present in the early universe
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PLANCK Surveyor
Map of first 10 degree strip of sky, dipole
subtracted
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PLANCK Surveyor
Zoom in on 10 degree square at high Galactic
latitude, with LFI at 70 GHz, HFI at 100 GHz.
See fine structure in CMB, but also high redshift
dusty galaxies
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PLANCK Surveyor
Zoom in on 10 degree area in Galactic plane, in 9
bands. Will learn about very cool dust in our
Galaxy.
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Atacama Large Millimetre Array
ALMA is a joint European-US- Japenese mm and
submm array, starting operations next year.
Will allow us to map submillimetre sources to 0.1
arcsec resolution.
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how to detect z 10 galaxies, image exoplanets ?
James Webb Space Telescope
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European-ELT
Proposed 43-m, segmented mirror, working at
0.6-23 microns. Will allow us to image
exoplanets, and to see the very first galaxies in
the universe, at redshift gt 10
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History of the universe